| 1. Lower-level management function most effectively when they have thorough training and unimpeded communication with workers, supervisors, and one another.
(A) management function most effectively when they have
(B) managers function most effectively when they have
(C) management functions most effectively when they have
(D) managers function most effectively when they have received（B）
(E) management functions most effectively when it has
D选想错在哪里？为什么不能说have received training? | 
